Measuring VTC parameters of a digital IC

To measure the VTC parameters for SN7402, I had the following schematics:

For V_OH:                                                              

          

For V_OL: 

       

How did I come up with the resistances? Here's how - per the datasheet, the required V_OH was 3.4 V and V_OL was 0.2V.

With Required V_OH =3.4 V for I_OH= - 0.4 mA (per datasheet), which gave me pulldown resistor as:

Similarly, the Required V_OL =0.2 V for I_OL= 16 mA (datasheet) and V_CC=4.75 V gave me the pullup resistor as:

But since calculated resistances weren’t available, following values were used-

R_pull-down=8.1 kW

R_pull-up= 268 kW

Here is the result of my folly:

	As Measured	From Datasheet
VOH	3.38 V	3.4 V  (Test conditions: Vcc=4.75V, IOH= - 0.4 mA)
VOL	0.220 V	0.2 V (Test conditions: Vcc=4.75V, IOL= 16 mA)

The measured value is different from the datasheet since I had used different resistors. Note the Logic Swing of the output was 3.16V.